TPi May 2018

products & developments Sealing hydroelectric pipes

gasket manufacturer VIP Polymers Ltd was commissioned to sup- ply its VIP-Weco internal seals to repair the leaks without the need for time-consuming and costly excavation. The water tightness problemhad been caused by settlement of the 6m pipe sections within the trench infill.

A hydroelectric water pipe that carries water from a river to a power generator has been sealed at multiple points using the no-dig VIP-Weco pipe rehabilitation system. Joints at eight locations along the 1.5 km pipe near Inverness in the Scottish Highlands had not been water tight to the pressure standard demanded for the 1.35MW power project. Seal and

Hydroelectric water pipe sealed by VIP-Weco, located on a mountainside near Inverness

A final seal was installed where the pipe stepped down from 1,600 to 1,400mm, with a section of 1,600mm ductile iron between the two. A bespoke seal was manufactured, with an extra retention band, to accommodate the 200mm variance in pipe diameters. Minimising downtime was essential to the success of the pipe rehabilitation project. The metal retaining bands for each seal were supplied in two sections, making them easier to transport into and along the pipe. Five VIP-Weco seals were installed in one day, with the quickest installation time being just 16 minutes. Two more seals were installed the following day, and the final seal was installed two weeks later, in line with the client’s operational requirements. VIP was commissioned to supply the seals by Fusion Pipe Products, and the installation was carried out by authorised VIP-Weco installer JM Contracting. Seven of the seals selected for the pipe rehabilitation project were 280mm wide. The reducer seal was 480mm wide, to accommodate the difference in pipe diameter. These wider seals can be supplied with other configurations, for example to accommodate extreme longitudinal cracking. Both widths can be used on circular, elliptical and egg-shaped profiles. The quantity of retention bands supplied is dependent on the infiltration pressure rating requirement.

VIP business development manager Jim Shaw said, “Our VIP-Weco seals achieved the desired results with complete success, and with minimum disruption to the operation of the hydro power scheme. The defective joints were located along a 100m stretch of the pipe, which began 80m from the entry point. The partners involved in the hydro project urgently wanted a solution that was quick and cost effective to deploy.” VIP-Weco seals are used for trenchless rehabilitation of pipes for water, fuel and gas. They use WRAS-approved material, comply fully with BS6920, and have a typical life expectancy of 50+ years. Rubber sleeves made from EPDM or NBR compounds are applied to the inner wall of the pipe, and held in place by stainless steel retaining bands to create a safe, durable mechanical sealing solution. The hydroelectric pipe, which was designed to have a working pressure of 1.5 bar, was found to be unable to hold its hydrostatic test pressure of 12 bar at the eight joints. VIP-Weco seals were installed at five locations where the pipe was 1,600mm in diameter and made from GRP, and two points where it was 1,400mm in diame- ter and made from polyethylene.

The two-part retention band design aided quick installation 80m from the pipe entry point

VIP Polymers Ltd – UK sales@vip-polymers.com www.vip-polymers.com

The reducer seal in place, demonstrating the flexibility of the VIP-Weco system

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TUBE PRODUCTS INTERNATIONAL May 2018

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